Cersei, the scheming queen mother of King Tommen, had a bad season. First, her son, the monstrous King Joffrey, died. Then, her beloved brother-boyfriend (eww) came back from war mutilated. Then, her father threatened to marry her off to Loras Tyrell. But at least she has the unethical not-maester Qyburn to resurrect the body of the giant Gregor Clegane for her.
When last we saw Cersei, she was seducing Jaime; prior to this, she had rejected him, saying he returned to her "too late."
Chances of survival
High for season 5, not good after that. As with Tyrion, Cersei will make it to the bitter end, but then she'll also be ended. Considering how many good guys die in this show, it's easy to forget that the bad guys are also thinned out. Also, there's this prophecy.